Fluid turbine with vortex generators

ABSTRACT

The present disclosure relates to fluid turbines having a turbine shroud assembly formed with mixing elements (e.g., both inwardly and outwardly curving elements) having airfoil cross sections. These airfoils form ringed airfoil shapes that provide a means of controlling the flow of fluid over the rotor assembly or over portions of the rotor assembly. The fluid dynamic performance of the ringed airfoils directly affects the performance of the turbine rotor assembly. The mass and surface area of the shrouds result in load forces on support structures. By delaying or eliminating the separation of the boundary layer over the ringed airfoils, boundary layer energizing members (e.g., vortex generators, flow control ports) on the ringed airfoils increase the power output of the fluid turbine system and allow for relatively shorter chord-length airfoil cross sections and therefore reduced mass and surface area of the shroud assemblies.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser.No. 61/622,294 filed Apr. 10, 2012, the contents of which is hereinincorporated by reference in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to fluid turbine systems (e.g., wind orwater turbines) and, more particularly to fluid turbine systems having arotor assembly in fluid communication with a shroud assembly (e.g.,turbine shroud assembly) having boundary layer energizing members (e.g.,vortex generators, flow control ports). The present disclosure furtherrelates to fluid turbine systems having a shroud assembly with reducedsurface area and or mass.

2. Background

In general, some conventional horizontal axis fluid turbines used forpower generation have blades (e.g., two to five open blades) arrangedlike a propeller, the blades typically being mounted to a horizontalshaft attached to a gear box which drives a power generator. Attemptshave been made to provide a means of delaying or preventing flowseparation between the flowing fluid and the blade surfaces.

Example fluid turbines are described and disclosed in U.S. Pat. Nos.8,021,100; and 8,393,850, and U.S. Patent Pubs. Nos. 2011/0014038;2010/0270802; 2010/0247289; 2011/0002781; 2011/0020107; 2011/0085901;2011/0135460; 2010/0166547; 2010/0133853; and 2012/0070275, the entirecontents of each being hereby incorporated by reference in theirentireties.

SUMMARY

An interest exists for advantageous fluid turbine systems that providean improved means of delaying or preventing flow separation over a flowcontrol surface (e.g., over the turbine shroud assembly), for improvingthe performance of the turbine system and or rotor assembly. These andother opportunities for improvement are addressed and or overcome by theassemblies, systems and methods of the present disclosure.

The present disclosure provides improved fluid turbine systems. Moreparticularly, the present disclosure provides advantageous fluid turbinesystems having a rotor assembly in fluid communication with a shroudassembly (e.g., a turbine shroud assembly in the shape of an airfoil orringed airfoil), the shroud assembly having boundary layer energizingmembers (e.g., vortex generators, flow control ports). The presentdisclosure also provides for improved fluid turbine systems having ashroud assembly with reduced surface area and or mass. In exampleembodiments, the reduction of surface area provides a means of reducingload forces and or tower stress forces (e.g., in excessive fluid flowconditions).

In general, the present disclosure provides fluid turbine systems havingboundary layer energizing members (e.g., vortex generators, flow controldevices or ports). The boundary layer energizing members areadvantageously configured and dimensioned to prevent separation of afluid boundary layer over the turbine shroud assembly and or over theejector shroud assembly to alter or improve the performance of the fluidturbine system.

In general, there are many situations in which it can be desirable toprovide a means of delaying or preventing flow separation between aflowing medium and a flow control surface. For example, a fluid passingover an airfoil surface from the leading edge to the trailing edgetypically flows from a region with low static pressure to a region withhigh static pressure. This can result in forces which tend to retard theboundary layer and cause the fluid to separate, resulting in increasedseparation-drag and therefore reduced lift and reduced performance ofthe airfoil. Boundary layer energizing members (e.g., vortexgenerators), associated with the flow control surface, can be used tosubstantially prevent and or minimize flow separation by mixing freeflow with the boundary layer. As used herein, the term “boundary layer”refers to the layer of fluid flow in the immediate vicinity of a flowcontrol surface. One skilled in the art will recognize that a boundarylayer is involved or included in all embodiments of the presentdisclosure where a flowing fluid or medium is flowing over a flowcontrol surface.

In general, a properly designed shroud or duct delivers greater massflow rate to the interior of the shroud or duct than to the exterior. Assuch, improved performance over that of a similar open-rotor system canbe achieved from a rotor in fluid communication with a properly designedshroud or duct. In example embodiments of the present disclosure,boundary layer energizing members provide a means of delaying orpreventing flow separation over a flow control surface (e.g., over theturbine shroud assembly), thereby advantageously allowing for thereduction of flow control surface area (e.g., turbine shroud assemblysurface area or airfoil surface area), while maintaining or increasingperformance characteristics similar to that of a relatively larger flowcontrol surface area (e.g., an airfoil with a larger chord). Moreover,the reduction of surface area and mass also reduces loads and towerstress forces (e.g., in high velocity fluid flow conditions) of theturbine systems of the present disclosure.

In example embodiments, the present disclosure advantageously providesfor turbine systems that include vortex generators or the like mountedwith respect to shroud surfaces (e.g., to the suction side of shroudassembly or ringed airfoil surfaces), the vortex generators areconfigured and dimensioned to generate vortices (vortexes) that energizeor provide energy to the boundary layer to delay or prevent flowseparation before the fluid has reached the trailing edge of the shroudassembly. In example embodiments, a vortex generator is a device ormember that is configured and dimensioned to generate a vortex orvortices (vortexes) or the like, thereby providing energy to orenergizing (via the generated vortex) a fluid boundary layer over asurface of the turbine system (e.g., over the turbine shroud assembly),which can alter the fluid boundary layer over a surface of the turbinesystem (e.g., to delay or prevent flow separation before the fluid hasreached the trailing edge of the shroud assembly). In certainembodiments and as discussed further below, the shroud assemblies of thepresent disclosure take the form of ringed airfoils (e.g., substantiallycircular in form), although the present disclosure is not limitedthereto. Rather, the shroud assemblies of the present disclosure cantake a variety of forms (e.g., assemblies or airfoils having anon-circular shape; assemblies or airfoils that include gaps of sectionsalong their circumference, periphery or shape; etc.).

In certain embodiments, the lift-side airfoil cross-sections of a shroudassembly or ringed airfoil are on the interior surface of the shroudassembly or ring. In other embodiments, a majority or plurality of thelift-side airfoil cross-sections of the shroud assembly are on theinterior surface, while portions of the interior surface of the shroudassembly can also include pressure-side airfoil cross-sections, and orportions of the outer surface of the ringed airfoil or shroud assemblymay include lift-side airfoil cross-sections.

An airfoil assembly (e.g., ringed airfoil assembly) that surrounds or isdisposed about a rotor assembly is typically known as a turbine shroudassembly. In general, the turbine shroud assembly is generallycylindrical and is configured to generate relatively lower pressurewithin the turbine shroud assembly (the interior of the shroud) andrelatively higher pressure outside the turbine shroud (the exterior ofthe shroud). The shroud assembly or ringed airfoil can be cambered, andhave cross-sections shaped like an aircraft wing airfoil. In exampleembodiments, the turbine shroud assembly includes inward and outwardlycurving mixing elements that have airfoil cross sections.

In certain embodiments, boundary layer energizing members (e.g., vortexgenerators) on the pressure side of the turbine shroud assembly,proximal to the inward turning mixing elements, prevent or minimizeseparation of the portion of the fluid stream that provides mixing ofbypass flow with flow that has passed through the rotor assembly. Theturbine shroud assembly can include mixing elements such as, forexample, mixing lobes or slots.

In some embodiments, a second shroud assembly may be located proximal oradjacent to the trailing edge of the turbine shroud assembly, and thesecond shroud assembly is typically known as an ejector shroud assembly.For example, the ejector shroud assembly can take the form or shape of aringed airfoil that includes an annular ring having members with airfoilcross sections, although the present disclosure is not limited thereto.In example embodiments, boundary layer energizing members (e.g., vortexgenerators) mounted with respect to the suction side of the ejectorshroud assembly prevent flow separation until the fluid stream haspassed the trailing edge of the turbine system.

Load forces (e.g., originating from the shrouded system) on supportstructures, such as tower and foundation components, of a turbine systemmay be caused by drag and or side loads on aerodynamic surfaces of theturbine system. Boundary layer energizing members delay or substantiallyeliminate or minimize the separation of the boundary layer over flowcontrol surfaces (e.g., airfoils), providing a means of employingairfoil cross sections with relatively shorter chord lengths than thatof airfoils with similar performance characteristics. It is noted that areduction in the chord length can provide a ringed airfoil with reducedsurface area and therefore, reduced loads, drag and or reduced tower andfoundation stress.

Some mixer-ejector turbines employ mixing elements such as diverging andconverging airfoil segments. In general, such mixing elements providecontrolled stream-wise vorticity in the area downstream of themixer-ejector turbine. It is noted that a faceted trailing edgeconfiguration of the turbine also provides similarly controlledstream-wise vorticity. In example embodiments, the fluid turbine systemshaving faceted segments with the substantially annular airfoils providesappropriate surface area for load mitigation by having a shorter turbineshroud and a longer ejector shroud.

In general, reducing lift forces over turbine aerodynamic surfaces,particularly when the turbine is in a parked configuration, reducesloads on turbine structural components. In certain embodiments, theaerodynamic augmentation provided by vortex generators may also beachieved by flow control devices or ports (e.g., active flow controldevices). An advantage of flow control devices is that they can eitherprevent or cause separation over a flow control surface. In general,introducing fluid (e.g., air) normal to the airfoil surface can preventflow separation. Lift forces over the shroud surfaces when the turbineis in a parked configuration can cause unintended yaw moment forces andtherefore, undue stress on structural components. In exampleembodiments, by controlling the volume of airflow and or the angle offlow to the airfoil surface, boundary layer separation can be caused,effectively stalling the airfoil and reducing the lift force andtherefore the yaw moment. A reduced yaw moment reduces the loads onturbine structural components.

The present disclosure provides for a shrouded fluid turbine systemincluding a rotor assembly; a turbine shroud assembly disposed about therotor assembly, the turbine shroud having a low pressure side and a highpressure side, the low pressure side in fluid communication with therotor assembly; and at least one boundary layer energizing memberassociated with the turbine shroud assembly, the at least one boundarylayer energizing member configured and dimensioned to alter a fluidboundary layer over a surface of the turbine shroud assembly to alterthe performance of the fluid turbine system.

The present disclosure also provides for a shrouded fluid turbine systemwherein the at least one boundary layer energizing member is positionedproximal to a leading edge of the turbine shroud assembly. The presentdisclosure provides for a shrouded fluid turbine system furtherincluding a first plurality of boundary layer energizing members and asecond plurality of boundary layer energizing members; wherein the firstplurality of boundary layer energizing members are positioned proximalto a leading edge of the turbine shroud assembly; and wherein the secondplurality of boundary layer energizing members are positioned betweenthe leading edge and a trailing edge of the turbine shroud assembly.

The present disclosure provides for a shrouded fluid turbine systemwherein the first and second pluralities of boundary layer energizingmembers are associated with the low pressure side of the turbine shroudassembly. The present disclosure provides for a shrouded fluid turbinesystem further including a plurality of boundary layer energizingmembers; wherein the turbine shroud assembly includes a plurality ofcurving mixing elements; and wherein each mixing element is associatedwith at least one boundary layer energizing member. The presentdisclosure provides for a shrouded fluid turbine system wherein theplurality of curving mixing elements includes a first plurality ofinwardly curving mixing elements and a second plurality of outwardlycurving mixing elements. The present disclosure provides for a shroudedfluid turbine system wherein at least one boundary layer energizingmember is positioned on the high pressure side of the turbine shroudassembly and proximal to an inward curving mixing element of theplurality of inward curving mixing elements.

The present disclosure provides for a shrouded fluid turbine systemwherein the turbine shroud assembly defines an airfoil ring having anapex; and wherein the at least one boundary layer energizing member ispositioned proximal to the apex of the airfoil ring. The presentdisclosure provides for a shrouded fluid turbine system wherein the atleast one boundary layer energizing member is a vortex generator, thevortex generator in the form of a protruding member that protrudes froma surface of the turbine shroud assembly. The present disclosureprovides for a shrouded fluid turbine system wherein the vortexgenerator has a length and a height; and wherein the length is aboutfour times the height of the vortex generator. The present disclosureprovides for a shrouded fluid turbine system wherein the vortexgenerator has a length and a height; wherein the vortex generator isfabricated from a flexible material and includes a first un-flexedcondition and a second flexed condition; and wherein when the vortexgenerator is in the second flexed condition, the length of the vortexgenerator is about eight times the height.

The present disclosure provides for a shrouded fluid turbine systemwherein each curving mixing element includes a voluminous leading edgethat transitions to a curved planar form at a trailing edge. The presentdisclosure provides for a shrouded fluid turbine system furtherincluding an ejector shroud assembly positioned downstream from andcoaxial with the turbine shroud assembly; wherein at least one boundarylayer energizing member is associated with the ejector shroud assembly,the at least one boundary layer energizing member associated with theejector shroud assembly configured and dimensioned to alter a fluidboundary layer over a surface of the ejector shroud assembly to alterthe performance of the fluid turbine system.

The present disclosure provides for a shrouded fluid turbine systemwherein the at least one boundary layer energizing member associatedwith the ejector shroud assembly is positioned proximal to a leadingedge of the ejector shroud assembly. The present disclosure provides fora shrouded fluid turbine system further including a first plurality ofboundary layer energizing members and a second plurality of boundarylayer energizing members associated with the ejector shroud assembly;wherein the first plurality of boundary layer energizing members arepositioned proximal to a leading edge of the ejector shroud assembly;and wherein the second plurality of boundary layer energizing membersare positioned between the leading edge and a trailing edge of theejector shroud assembly.

The present disclosure provides for a shrouded fluid turbine systemwherein the first and second pluralities of boundary layer energizingmembers are associated with the low pressure side of the ejector shroudassembly. The present disclosure provides for a shrouded fluid turbinesystem wherein the ejector shroud assembly defines an airfoil ringhaving an apex; and wherein the at least one boundary layer energizingmember associated with the ejector shroud assembly is positionedproximal to the apex of the airfoil ring. The present disclosureprovides for a shrouded fluid turbine system wherein the at least oneboundary layer energizing member associated with the ejector shroudassembly is a vortex generator, the vortex generator in the form of aprotruding member that protrudes from a surface of the ejector shroudassembly.

The present disclosure provides for a shrouded fluid turbine systemwherein the at least one boundary layer energizing member is a flowcontrol port, the flow control port configured and dimensioned to employhigh velocity flow through the flow control port for flow controlpurposes and to alter a fluid boundary layer over a surface of theturbine shroud assembly to alter the performance of the fluid turbinesystem. The present disclosure provides for a shrouded fluid turbinesystem wherein the at least one flow control port is positioned proximalto a leading edge of the turbine shroud assembly. The present disclosureprovides for a shrouded fluid turbine system wherein the at least oneflow control port is remotely energized with the high velocity flow. Thepresent disclosure provides for a shrouded fluid turbine system whereinthe at least one flow control port is energized with the high velocityflow by harvesting fluid energy from the fluid turbine system.

The present disclosure provides for a shrouded fluid turbine systemwherein the at least one boundary layer energizing member is configuredand dimensioned to prevent separation of a fluid boundary layer over asurface of the turbine shroud assembly to alter the performance of thefluid turbine system. The present disclosure provides for a shroudedfluid turbine system wherein the at least one boundary layer energizingmember is configured and dimensioned to alter a fluid boundary layerover a surface of the turbine shroud assembly to reduce the performanceof the fluid turbine system.

The present disclosure provides for a shrouded fluid turbine systemwherein the turbine shroud assembly defines an annular airfoil having aleading edge that transitions to a faceted trailing edge. The presentdisclosure provides for a shrouded fluid turbine system wherein thevolume or angle of the high velocity flow through the flow control portis variable. The present disclosure provides for a shrouded fluidturbine system wherein the at least one boundary layer energizing memberconfigured and dimensioned to alter a fluid boundary layer over asurface of the turbine shroud assembly alters the performance of thefluid turbine system.

The present disclosure provides for a shrouded fluid turbine systemincluding a rotor assembly; a turbine shroud assembly disposed about therotor assembly, the turbine shroud having a low pressure side and a highpressure side, the low pressure side in fluid communication with therotor assembly, the turbine shroud assembly including a plurality ofcurving mixing elements; and a first and second plurality of boundarylayer energizing members associated with the turbine shroud assembly,each boundary layer energizing member configured and dimensioned toalter a fluid boundary layer over a surface of the turbine shroudassembly, the first plurality of boundary layer energizing memberspositioned proximal to a leading edge of the turbine shroud assembly andthe second plurality of boundary layer energizing members positionedbetween the leading edge and a trailing edge of the turbine shroudassembly, at least a portion of the first and second pluralities ofboundary layer energizing members associated with the low pressure sideof the turbine shroud assembly, and each mixing element associated withat least one boundary layer energizing member.

The present disclosure provides for a shrouded fluid turbine systemincluding a rotor assembly; a turbine shroud assembly disposed about therotor assembly, the turbine shroud having a low pressure side and a highpressure side, the low pressure side in fluid communication with therotor assembly; at least one first boundary layer energizing memberassociated with the turbine shroud assembly, the at least one firstboundary layer energizing member configured and dimensioned to alter afluid boundary layer over a surface of the turbine shroud assembly toalter the performance of the fluid turbine system; an ejector shroudassembly positioned downstream from and coaxial with the turbine shroudassembly; at least one second boundary layer energizing memberassociated with the ejector shroud assembly, the at least one secondboundary layer energizing member configured and dimensioned to alter afluid boundary layer over a surface of the ejector shroud assembly toalter the performance of the fluid turbine system; wherein the turbineshroud assembly includes a plurality of curving mixing elements; whereinthe at least one first boundary layer energizing member is positionedproximal to a leading edge of the turbine shroud assembly; and whereinthe at least one second boundary layer energizing member is positionedproximal to a leading edge of the ejector shroud assembly.

These and other non-limiting features or characteristics of the presentdisclosure will be further described below. Any combination orpermutation of embodiments is envisioned. Additional advantageousfeatures, functions and applications of the disclosed assemblies,systems and methods of the present disclosure will be apparent from thedescription which follows, particularly when read in conjunction withthe appended figures. All references listed in this disclosure arehereby incorporated by reference in their entireties.

BRIEF DESCRIPTION OF THE DRAWINGS

The following is a brief description of the drawings, which arepresented for the purposes of illustrating the disclosure set forthherein and not for the purposes of limiting the same. Exampleembodiments of the present disclosure are further described withreference to the appended figures. It is to be noted that the variousfeatures and combinations of features described below and illustrated inthe figures can be arranged and organized differently to result inembodiments which are still within the spirit and scope of the presentdisclosure. To assist those of ordinary skill in the art in making andusing the disclosed systems, assemblies and methods, reference is madeto the appended figures, wherein:

FIG. 1 is a front perspective view of an embodiment of a fluid turbinesystem;

FIG. 2 is a rear perspective view of the system of FIG. 1;

FIGS. 3-4 are front, side perspective, detail views of the system ofFIG. 1;

FIG. 5 is a rear, side perspective, detail view of the system of FIG. 1;

FIG. 6 is a side cross-sectional, detail view of the system of FIG. 1depicting the proportion between the length and height of a vortexgenerator and the length and height of the airfoil member that it isengaged with;

FIG. 7 is a side cross-sectional, detail view of the system of FIG. 1depicting the proportion between the length and height of a vortexgenerator and the length and height of the airfoil member that it isengaged with;

FIGS. 8-10 are side, cross section detail views of embodiments of thesystem of FIG. 1;

FIGS. 11-12 are detailed, cross sectional views of additionalembodiments of a vortex generator of a shrouded fluid turbine of thepresent disclosure;

FIG. 13 is a front perspective view of another embodiment of a fluidturbine system of the present disclosure;

FIGS. 14-16 are detailed cross sectional views of the system of FIG. 13;

FIG. 17 is a front perspective view of another embodiment of a fluidturbine system of the present disclosure depicting boundary layerenergizing members;

FIG. 18 is a front, right-perspective, detailed cross section of thesystem of FIG. 17;

FIG. 19 is a side detailed cross section of the system of FIG. 17;

FIG. 20 is a front right, detailed cross section view of the system ofFIG. 17;

FIG. 21 is a front perspective view of another embodiment of a fluidturbine system of the present disclosure depicting boundary layerenergizing members;

FIG. 22 is a front right perspective view of another embodiment of afluid turbine system of the present disclosure;

FIG. 23 is a front, right perspective, detailed cross section view ofthe system of FIG. 22 depicting boundary layer energizing members; and

FIG. 24 is a side, detailed cross section view of the system of FIG. 22.

DETAILED DESCRIPTION

The example embodiments disclosed herein are illustrative ofadvantageous fluid turbine systems, and assemblies of the presentdisclosure and methods or techniques thereof. It should be understood,however, that the disclosed embodiments are merely examples of thepresent disclosure, which may be embodied in various forms. Therefore,details disclosed herein with reference to example fluid turbine systemsor fabrication methods and associated processes or techniques ofassembly and or use are not to be interpreted as limiting, but merely asthe basis for teaching one skilled in the art how to make and use theadvantageous fluid turbine systems of the present disclosure.

A more complete understanding of the components, processes, andapparatuses disclosed herein can be obtained by reference to theaccompanying figures. These figures are intended to demonstrate thepresent disclosure and are not intended to show relative sizes anddimensions or to limit the scope of the example embodiments.

Although specific terms are used in the following description, theseterms are intended to refer only to particular structures in thedrawings and are not intended to limit the scope of the presentdisclosure. It is to be understood that like numeric designations referto components of like function.

The term “about” when used with a quantity includes the stated value andalso has the meaning dictated by the context. For example, it includesat least the degree of error associated with the measurement of theparticular quantity. When used in the context of a range, the term“about” should also be considered as disclosing the range defined by theabsolute values of the two endpoints. For example, the range “from about2 to about 4” also discloses the range “from 2 to 4.”

In certain embodiments, a mixer-ejector fluid turbine provides animproved means of generating power from fluid currents. A turbine shroudassembly can be disposed about a rotor assembly, with the rotor assemblyextracting power from a primary fluid stream. A mixer-ejector pump canbe included in some embodiments that ingests flow from the primary fluidstream and secondary flow, and promotes turbulent mixing of the twofluid streams. This enhances the power system by increasing the amountof fluid flow through the system, increasing the velocity at the rotorassembly for more power availability, and reducing back pressure onturbine blades.

The term “rotor assembly” is used herein to refer to any assembly inwhich blades are attached to a shaft and able to rotate, allowing forthe generation of power or energy from fluid rotating the blades. Rotorassemblies can include a propeller-like rotor or a rotor or statorassembly. Any type of rotor assembly may be utilized with the fluidturbines of the present disclosure.

In certain embodiments, the leading edge of a turbine shroud assemblymay be considered the front of the fluid turbine system, and thetrailing edge of a turbine shroud assembly or of an ejector shroudassembly may be considered the rear of the fluid turbine system. A firstcomponent of the fluid turbine system located closer to the front of theturbine system may be considered “upstream” of a second componentlocated closer to the rear of the turbine system. Put another way, thesecond component is “downstream” of the first component.

The present disclosure provides advantageous fluid turbine systems. Moreparticularly, the present disclosure provides improved fluid turbinesystems having a rotor assembly in fluid communication with a shroudassembly (e.g., turbine shroud assembly) having boundary layerenergizing members (e.g., vortex generators, flow control ports). Thepresent disclosure also provides for improved fluid turbine systemshaving a shroud assembly with reduced surface area and or mass. Ingeneral, the reduction of surface area provides a means of reducing loadforces and tower stress forces in excessive fluid flow conditions.

In example embodiments, the present disclosure provides shrouded fluidturbines (e.g., wind or water turbines) having a shroud assembly formedwith both inward and outwardly curving elements having airfoil crosssections. These airfoils form ringed airfoil shapes that provide a meansof controlling the flow of fluid over the rotor assembly and or overportions of the rotor assembly. In general, the fluid dynamicperformance of the ringed airfoils directly affects the performance ofthe turbine rotor assembly. The mass and surface area of the shroudassemblies result in load forces on support structures. By delaying oreliminating the separation of the boundary layer over the ringedairfoils, boundary layer energizing members (e.g., vortex generators,flow control ports) on the ringed airfoils increase the power output ofthe fluid turbine system and allow for relatively shorter chord-lengthairfoil cross sections and therefore reduced mass and surface area ofthe shroud assemblies.

In certain embodiments, the present disclosure provides for a fluidturbine system including a turbine shroud assembly (e.g., ringed turbineshroud) that surrounds a rotor assembly, and can further include in someembodiments an ejector shroud assembly that surrounds the exit of theturbine shroud assembly. It is noted that the fluid turbine system ofthe present disclosure may or may not include an ejector shroudassembly, as further discussed below. In general, boundary layerenergizing members (e.g., vortex generators, flow control ports) areassociated with the turbine shroud assembly and or ejector shroudassembly for the purpose of preventing flow separation of the boundarylayer.

The term vortex generator is used to describe a range of assemblies ordevices mounted with respect to a turbine system. The term vortexgenerator can mean, but is in no way limited to, “device or membergenerating a vortex.” For example, a vortex generator can be aprotruding member such as illustrated throughout the figures. However,one skilled in the art will readily recognize numerous suitable vortexgenerator forms or shapes may be utilized in practicing the presentdisclosure, and therefore the recited embodiments of the figures are notintended to be limiting in scope.

Referring now to the drawings, like parts are marked throughout thespecification and drawings with the same reference numerals,respectively. Drawing figures are not necessarily to scale and incertain views, parts may have been exaggerated for purposes of clarity.

FIG. 1 is a front perspective view of an example embodiment of a fluidturbine system 100 (e.g., shrouded fluid turbine system) of the presentdisclosure. FIG. 2 is a rear perspective view of the fluid turbinesystem 100 of FIG. 1. In general, a system having a rotor or impellerassembly 140 encircled in part or completely by one or more shroudassemblies 110, 120 can be described as a shrouded fluid turbine system100.

Referring to FIGS. 1 and 2, the shrouded fluid turbine system 100includes a turbine shroud 110, a nacelle body or housing 150, a rotorassembly 140, and in some embodiments an ejector shroud assembly 120. Itis noted that the shrouded fluid turbine system 100 may or may notinclude an ejector shroud assembly 120, as further discussed below. Inembodiments that include the ejector shroud assembly 120, supportmembers 106 (e.g., trusses, attachment struts) connect the turbineshroud assembly 110 to the ejector shroud assembly 120.

The turbine shroud assembly 110 includes a front end 112, also known asan inlet end or a leading edge. The turbine shroud assembly 110 alsoincludes a rear end 116, also known as an exhaust end or trailing edge.In some embodiments, the ejector shroud 120 includes a front end, inletend or leading edge 122, and a rear end, exhaust end, or trailing edge124.

The rotor assembly 140 surrounds the nacelle body 150. The rotorassembly 140 includes a central hub 141 at the proximal end of the rotorblades. The central hub 141 is rotationally engaged with the nacellebody 150. The nacelle body 150 and the turbine shroud assembly 110 aresupported by a tower 102. The rotor assembly 140, turbine shroudassembly 110, and ejector shroud assembly 120 can be coaxial with eachother, i.e., they share a common central axis 105 (FIG. 2). It is notedthat the terms inward or inwardly and outward or outwardly in regards tothe mixing elements 115, 117 discussed below are relative to the centralaxis 105.

Although turbine shroud assembly 110 is shown encompassing or encirclingthe rotor assembly 140, in some embodiments, the turbine shroud assembly110 can partially encompass or encircle the rotor assembly 140 (e.g.,the turbine shroud assembly 110 may have gaps, have slots, bediscontinuous, segmented, and the like, or the rotor assembly 140 mayextend beyond the leading edge 122 or trailing edge 124 of the turbineshroud assembly 110). See, e.g., U.S. Patent Pub. No. 2010/0247289 forexample shrouds that are segmented. Moreover, the ejector shroudassembly 120, if present, may have gaps, have slots, be discontinuous,segmented, and the like. In some embodiments, the turbine shroudassembly 110 may not encircle the rotor assembly 140 (e.g., at least aportion of the rotor assembly 140 may be positioned in front of theleading edge 122 or past the trailing edge 124 of the turbine shroudassembly 110).

As noted, rotor assembly 140 refers to any assembly in which blades areattached to a shaft and able to rotate, allowing for the generation ofpower or energy from fluid rotating the blades. Rotor assemblies 140 caninclude a propeller-like rotor or a rotor or stator assembly. Any typeof rotor assembly 140 may be utilized with fluid turbine system 100.

In example embodiments, the turbine shroud assembly 110 has thecross-sectional shape of an airfoil, with the suction side (i.e., lowpressure side) on the interior of the shroud assembly 110. The rear end116 of the turbine shroud assembly 110 has mixing elements or lobes,including outwardly directed mixing elements 115 and inwardly directedmixing elements 117. The mixing elements 115, 117 extend downstreambeyond the rotor blades and are directed either outwardly or inwardlywith respect to the central axis 105. Put another way, the trailing edge116 of the turbine shroud assembly 110 is shaped to form two differentsets of mixing elements 115, 117. Inwardly directed mixing elements 117extend inwardly towards the central axis 105 of the mixer shroud.Outwardly directed mixing elements 115 extend outwardly away from thecentral axis 105. When viewed from the rear the mixing elements or lobes115, 117 form a general circular crenellated or circumferentialundulating in-and-out shape, as shown in FIG. 2. A pressure drop occursin the wake of the rotor assembly 140 as a result of the energy takenout by the rotor assembly 140. Inwardly and outwardly directed elements115, 117 provide turbulent mixing of high and low pressure streams, suchthat the fluid pressure in the wake of the turbine rapidly returns toambient pressure.

In certain embodiments, a mixer-ejector pump is formed by the ejectorshroud assembly 120 surrounding the ring of inwardly directed mixingelements 117 and outwardly directed mixing elements 115 of the turbineshroud assembly 110. In example embodiments, the airfoil defined by theejector shroud assembly 120 can have a generally cylindrical orring-like configuration having a circumferential body extending aboutthe central axis 105.

The mixing elements 115, 117 can extend downstream and into the inletend 122 of the ejector shroud assembly 120. In certain embodiments, themixer-ejector pump provides turbulent mixing of fluid that passesthrough the rotor assembly 140 with fluid that bypasses the rotorassembly 140. A pressure drop occurs in the wake of the rotor assembly140 as a result of the energy taken out by the rotor assembly 140.Inwardly and outwardly directed elements 115, 117 in combination withthe ejector shroud assembly 120 provide turbulent mixing of high and lowpressure streams, such that the fluid pressure in the wake of theturbine rapidly returns to ambient pressure.

In example embodiments, system 100 includes boundary layer energizingmembers 130. As shown in FIGS. 1-10, boundary layer energizing members130 take the form of vortex generators 130 (e.g., protruding members,etc.) or the like. In general, boundary layer energizing members 130 areconfigured and dimensioned to prevent separation of a fluid boundarylayer over flow control surfaces (e.g., over the turbine shroud assembly110 and or ejector shroud assembly 120) to alter or improve theperformance of the fluid turbine system 100 (or over shrouds 310, 320 ofsystem 300, or over shrouds 410, 420 of system 400, as discussed below).Stated another way, boundary layer energizing members 130 (e.g., vortexgenerators), associated with flow control surface (e.g., assembly 110,120) of system 100, can be used to substantially prevent and or minimizeflow separation by mixing free flow with the boundary layer. In certainembodiments, boundary layer energizing members 130 (e.g., vortexgenerators) are configured and dimensioned to energize the boundarylayer to delay or prevent flow separation before the fluid has reachedthe trailing edge of a flow control surface (e.g., shroud assembly 110and or 120) of system 100.

In example embodiments, a vortex generator 130 is a device or memberthat is configured and dimensioned to generate a vortex or vortices(vortexes) or the like, thereby providing energy to or energizing (viathe generated vortex) a fluid boundary layer over a surface of theturbine shroud assembly 110, which can alter the fluid boundary layerover a surface of the turbine shroud assembly 110 (e.g., to delay orprevent flow separation before the fluid has reached the trailing edgeof the shroud assembly). For example, vortex generators 130 can take theform of protruding members or the like, although the present disclosureis not limited thereto. Rather, protruding members 130 can take avariety of suitable forms or shapes. In example embodiments, theprotruding members 130 are designed so that they do not extend acrossthe diameter of the shrouds 110 and or 120, and are low profile having alimited aspect ratio. The term “energizing” can mean, but is in no waylimited to, providing energy or fluid flow to a system or location(e.g., to a fluid boundary layer over a surface of the turbine shroudassembly 110).

In general, at least one vortex generator 130 is mounted with respect toa surface of system 100 (e.g., to a surface of turbine shroud assembly110, or assembly 120). In example embodiments, a plurality of vortexgenerators 130 are mounted with respect to a surface of turbine shroudassembly 110 (or assembly 120). In some embodiments, the vortexgenerators 130 are integrally formed with assembly 110 (or assembly120), although the present disclosure is not limited thereto.

In certain embodiments and referring to FIGS. 3-4, vortex generators 130can be mounted with respect to the turbine shroud assembly 110approximately at or proximal to the leading edge 112 of the turbineshroud assembly 110. However, it is noted that vortex generators 130 canbe mounted with respect to assembly 110 (or assembly 120) at anysuitable location or position. For example, system 100 can includevortex generators 130 mounted with respect to the suction side (e.g.,low pressure side on the interior of the shroud assembly) and or withrespect to the pressure side (higher pressure side on the outside orexterior of the shroud assembly) of shroud assembly surfaces (assembly110 and or 120). As such, the vortex generators 130 can be configuredand dimensioned to energize the boundary layer to delay or prevent flowseparation before the fluid has reached the trailing edge of the shroudassembly 110, 120.

As shown in FIGS. 3-4, vortex generators 130 can be mounted with respectto the turbine shroud assembly 110 proximal to the leading edge 112 ofthe turbine shroud assembly 110 on the suction side (e.g., low pressureside on the interior of the shroud assembly 110—FIG. 4), and or on thepressure side (higher pressure side on the outside or exterior of theshroud assembly 110—FIG. 3). In example embodiments, the vortexgenerators 130 can be positioned substantially equidistantly apart fromone another around the circumference or periphery (suction or pressureside) of assembly 110 (or 120), although the present disclosure is notlimited thereto.

Additional vortex generators 130 can be mounted with respect to theturbine shroud assembly 110 near or proximal to the apex 111 of theairfoil ring defined by the interior of assembly 110 (e.g.,approximately at the thickest part of the cross sectional shape of theairfoil ring defined by assembly 110—FIG. 4). In some embodiments and asshown in FIG. 4, a plurality of vortex generators 130 can be arranged ordisposed in two or more circumferential rows about the surface of theshroud assembly 110. For example, the plurality of vortex generators 130can be arranged in a first downstream row (e.g, a row downstream of theblades of the rotor assembly 140) and in a second upstream row (e.g, arow upstream of the blades of the rotor assembly 140). In exampleembodiments and as shown in FIG. 4, assembly 110 includes a plurality ofvortex generators 130 positioned near or proximal to the apex 111 anddisposed in a circumferential row downstream of the blades of the rotorassembly 140. Assembly 110 also includes a plurality of vortexgenerators 130 proximal to the leading edge 112 and disposed in acircumferential row upstream of the blades of the rotor assembly 140.Again, it is noted that vortex generators 130 can be mounted withrespect to system 100 at any suitable location. Moreover, vortexgenerators 130 can be mounted with respect to the pressure side of theassembly 110 and proximal to the leading edge 112 of the turbine shroudassembly 110, and or proximal to the inward turning mixing elements 117(FIG. 3).

As noted, vortex generators 130 can be mounted with respect to ejectorshroud assembly 120 at any suitable location. As shown in FIG. 5, vortexgenerators 130 can be mounted with respect to ejector shroud assembly120 (e.g., on the suction or interior side) near or proximal to theleading edge 122 of the ejector 120, and additional vortex generators130 can be mounted with respect to the ejector shroud assembly 120between the leading edge 122 and the trailing edge 124 (e.g.,approximately located or positioned at the thickest part of the crosssectional shape of the airfoil ring defined by assembly 120).

FIGS. 6-7 illustrate the relative proportion of an embodiment of avortex generator 130 mounted with respect to the ejector shroud assembly120. As shown in FIG. 7, the height 144 of the vortex generator 130 isapproximately equal to about 1% of the chord length 140 of the airfoilcross-section defined by the ejector shroud assembly 120. Moreover, theheight 144 of the vortex generator 130 is approximately ¼th or 25% ofthe length 146 of the vortex generator 130. Put another way, the length146 of this particular vortex generator 130 is about four times theheight 144 of the vortex generator 130. It is important to note that thesize of the vortex generators are scaled to the physical properties ofthe location on the surface relative to the thickness of the boundarylayer and the desired effect. As such, it is noted that there are manypossible combinations of height 144 and/or length 146 of vortexgenerators 130 to generate different effects. For example and as shownin FIG. 7, in some embodiments the height 144 of the vortex generator130 may be configured and dimensioned to extend proximal to, aboveand/or past the boundary layer to displace energy or flow from the freestream flow above the boundary layer in order to prevent separation ofthe boundary layer over the surface of ejector shroud assembly 120. Insome embodiments, the energy displaced from the free stream flow istransferred or distributed to the boundary layer. In other embodiments,the height 144 of the vortex generator 130 does not extend above or pastthe boundary layer of a flow control surface of system 100. Again, thereare multiple permutations of height 144 and/or length 146 of vortexgenerators 130 to generate different effects.

FIG. 8 illustrates the relative difference in chord length between anairfoil cross section 160 without vortex generators, and an airfoilcross-section defined by the ejector shroud assembly 120 having vortexgenerators 130. The airfoil cross section 160 with chord length 152 isgreater than the chord length 142 of the airfoil cross-section definedby the ejector shroud assembly 120 having vortex generators 130. It hasbeen found that a shorter chord length 142, such as that of assembly 120having vortex generators 130 maintains and or improves upon theperformance of an airfoil cross section 160 that does not have vortexgenerators.

FIGS. 9-10 illustrate an example embodiment displaying the relativedifference in chord length between mixing element airfoil cross sections165, 167 without vortex generators, and with airfoil cross-sectionsdefined by mixing elements 115, 117 of assembly 110 having vortexgenerators 130. In certain embodiments, inward turning mixing elements117 introduce bypass flow (arrow 172) into the fluid stream that isdown-stream of the rotor assembly 140. The bypass flow 172 progressesalong the pressure side, or outer surface of the airfoil cross-sectiondefined by mixing element 117. Thus, vortex generators 130 positioned onthe outer surface of the mixing element 117 (FIG. 9) prevent separationof the fluid stream along the upper surface of the airfoil cross-sectiondefined by mixing element 117. The airfoil cross section 167 with chordlength 168 is relatively greater than the chord length 119 of theairfoil cross-section defined by mixing element 117. A shorter chordlength 119, such as that of airfoil cross-section 117 having vortexgenerators 130 maintains and or improves upon the performance of anairfoil cross section 167 that does not have vortex generators.

In example embodiments and as shown in FIG. 10, outwardly turning mixingelements 115 mix the flow (arrow 174) that has passed through the rotorassembly 140, with bypass flow in the fluid stream that is down-streamof the rotor assembly 140. The flow 174 progresses along the lift-side,or inner surface of the airfoil cross-section defined by mixing element115. Thus, vortex generators 130 positioned on the inner surface of themixing element 115 (FIG. 10) prevent separation of the fluid streamalong the inner surface of the airfoil cross-section defined by mixingelement 115. The airfoil cross section 165 with chord length 166 isrelatively greater than the chord length 186 of the airfoilcross-section defined by mixing element 115. A shorter chord length 186,such as that of airfoil cross-section 115 having vortex generators 130maintains and or improves upon the performance of an airfoil crosssection 165 that does not have vortex generators.

FIG. 11 is a detail, cross section view of an additional embodiment of avortex generator 130′ of the present disclosure. FIG. 12 is a anotherdetail cross sectional view of the vortex generator 130′ of FIG. 11.

FIGS. 11-12 illustrate a vortex generator 130′ that is fabricated atleast in part from a flexible material designed to change shape underset flow velocity conditions. For example, at times it can be beneficialto reduce the performance of a ringed airfoil (e.g., ringed airfoildefined by shroud assembly 110 or 120) proximal to a rotor assembly 140in high fluid velocity conditions. In one embodiment, the flexiblevortex generator 130′ may be utilized in shedding load on the shroudedturbine system 100 during periods of high fluid velocity. For example,the vortex generator 130′ can be mounted with respect to the lift orinterior side 223 of the ringed airfoil defined by shroud assembly 120(or at any other suitable location). The height 244 of the un-flexedvortex generator 130′ is approximately equal to 1% of the chord length242 of the airfoil cross section defined by shroud assembly 120. Thelength 246 of the vortex generator 130′ is, in this un-flexedconfiguration, approximately four times the height 244.

FIG. 12 illustrates vortex generator 130′ that is in a collapsed orflexed configuration as it would be in a fluid stream of a set velocity.The reduction of performance of the vortex generator 130′ causesseparation along the interior side 223 of the ringed airfoil defined byshroud assembly 120, and therefore provides a reduced performance of theairfoil with the intent to reduce the speed of the rotor assembly 140 inhigh velocity flow. In example embodiments and in this collapsed orflexed configuration as shown in FIG. 12, the length 247 of the vortexgenerator 130′ is approximately eight times the height 245.

FIG. 13 is a front perspective view of an additional embodiment of ashrouded fluid turbine system 300 of the present disclosure. FIGS. 14-15are detailed cross section views of the system 300 of FIG. 13.

Referring to FIGS. 13-15, the shrouded fluid turbine system 300 is amixer ejector turbine with airfoils that include single surfaceportions. The turbine system 300 includes a turbine shroud assembly 310,a nacelle body 350, a rotor assembly 340, and in some embodiments anejector shroud assembly 320. The turbine shroud assembly 310 includes afront end 312, also known as an inlet end or a leading edge. The turbineshroud assembly 310 also includes a rear end 316, also known as anexhaust end or trailing edge. The ejector shroud assembly 320 includes afront end, inlet end or leading edge 322, and a rear end, exhaust end,or trailing edge 324.

In example embodiments, the airfoil cross section defined by the turbineshroud assembly 310 includes a voluminous leading edge 312 thattransitions to a curved planar portion at the trailing edge 316. Theejector shroud assembly 320 includes a voluminous leading edge 322 thattransitions to a curved planar portion at the trailing edge 324.

The rotor assembly 340 surrounds the nacelle body 350. The rotorassembly 340 includes a central hub 341 at the proximal end of the rotorblades. The central hub 341 is rotationally engaged with the nacellebody 350. The nacelle body 350 and the turbine shroud assembly 310 aresupported by a tower 302. The rotor assembly 340, turbine shroudassembly 310, and ejector shroud assembly 320 can be coaxial with eachother, i.e. they share a common central axis 305. Support members 306connect the turbine shroud assembly 310 to the nacelle body 350.

In certain embodiments, the turbine shroud assembly 310 has thecross-sectional shape of an airfoil, with the suction side (i.e. lowpressure side) on the interior of the shroud assembly 310. The rear end316 of the turbine shroud assembly 310 has mixing elements, includingoutwardly directed mixing elements 315 and inwardly directed mixingelements 317. The mixing elements 315, 317 extend downstream beyond therotor blades and are directed either outwardly or inwardly with respectto the central axis 305. Put another way, the trailing edge 316 of theturbine shroud assembly 310 is shaped to form two different sets ofmixing elements 315, 317. Inwardly directed mixing elements 317 extendinwardly towards the central axis 305 of the mixer shroud. Outwardlydirected mixing elements 315 extend outwardly away from the central axis305.

A mixer-ejector pump is formed by the ejector shroud assembly 320surrounding the ring of inwardly directed mixing elements 317 andoutwardly directed mixing elements 315 of the turbine shroud assembly310. The mixing elements 315, 317 extend downstream and are proximate tothe inlet end 322 of the ejector shroud assembly 320. This mixer-ejectorpump provides turbulent mixing of fluid that passes through the rotorassembly 340 with fluid that bypasses the rotor assembly 340. A pressuredrop occurs in the wake of the rotor assembly 340 as a result of theenergy taken out by the rotor assembly 340. Inward and outwardlydirected elements 315, 317, in combination with the ejector shroudassembly 320 provide turbulent mixing of high and low pressure streams,such that the fluid pressure in the wake of the turbine rapidly returnsto ambient pressure.

In example embodiments, system 300 includes boundary layer energizingmembers 330. Similar to members 130 discussed above, boundary layerenergizing members 330 take the form of vortex generators 330 (e.g.,protruding members, etc.) or the like, although the present disclosureis not limited thereto. In general, boundary layer energizing members330 are configured and dimensioned to prevent separation of a fluidboundary layer over flow control surfaces (e.g., over the turbine shroudassembly 310 and or ejector shroud assembly 320) to alter or improve theperformance of the fluid turbine system 300 (or over shrouds 110, 120 ofsystem 100, or shrouds 410, 420 of system 400, as discussed above andbelow). Stated another way, boundary layer energizing members 330associated with flow control surface (e.g., assembly 310, 320) of system300, can be used to substantially prevent and or minimize flowseparation by mixing free flow with the boundary layer. In certainembodiments, boundary layer energizing members 330 (e.g., vortexgenerators) are configured and dimensioned to energize the boundarylayer to delay or prevent flow separation before the fluid has reachedthe trailing edge of a flow control surface (e.g., shroud assembly 310and or 320) of system 300.

FIGS. 14-15 illustrate vortex generators 330 mounted with respect to theoutwardly turning mixing elements 315, and with respect to the airfoildefined by the ejector shroud assembly 320. It is noted that an airfoilwith a voluminous leading edge that transitions to a curved planartrailing edge provides a reduction in the mass of the airfoil whilemaintaining performance. The introduction of vortex generators 330 onsuch an airfoil (e.g., mixing elements 315 and or airfoil defined by theejector shroud assembly 320) further reduces the material and thereforesurface area and mass of the airfoil while maintaining performancecharacteristics.

Vortex generators 330 energize the boundary layer over the inner surfaceof the outwardly turning mixing elements 315, to prevent separation overthe boundary layer. Outwardly turning mixing elements 315 mix the flowthat has passed through the rotor assembly 340, with bypass flow in thefluid stream down-stream of the rotor assembly 340. The flow 374progresses along the lift side, or inner surface of the airfoil, hence,vortex generators 330 prevent separation of the fluid stream along theinner surface of the airfoil defined by mixing elements 315.

FIG. 16 illustrates vortex generators 330 mounted with respect to theinward turning mixing element 317. Inward turning mixing elements 317introduce bypass flow (arrow 372) into the fluid stream down-stream ofthe rotor assembly 340. The bypass flow 372 progresses along thepressure side, or outer surface of the airfoil defined by the mixingelements 317, hence, vortex generators 330 prevent separation of thefluid stream along the upper surface of the airfoil defined by themixing elements 317.

In example embodiments, the airfoil defined by the mixing elements 317includes a voluminous leading edge 312 that transitions to a curvedplanar form at the trailing edge 316. The airfoil design coupled withvortex generators 330 provides an airfoil with the performancecharacteristics of a substantially larger and more massive airfoil.

Turning now to FIGS. 17-20, another example embodiment of a shroudedfluid turbine system is depicted in accordance with embodiments of thepresent disclosure. The fluid turbine system 400 includes a turbineshroud assembly 310, a nacelle body 350, a rotor assembly 340, and insome embodiments an ejector shroud assembly 320. The turbine shroudassembly 310 includes a front end 312 and a rear end 316, and theejector shroud assembly 320 includes a leading edge 322, and trailingedge 324.

The rotor assembly 340 includes a central hub 341, and the nacelle body350 and the turbine shroud assembly 310 are supported by a tower 302.The rotor assembly 340, turbine shroud assembly 310, and ejector shroudassembly 320 can be coaxial with each other, i.e. they share a commoncentral axis 305. Support members 306 connect the turbine shroudassembly 310 to the nacelle body 350. The rear end 316 of the turbineshroud assembly 310 has mixing elements, including outwardly directedmixing elements 315 and inwardly directed mixing elements 317. It isnoted that like reference numbers refer to like components.

In certain embodiments and as shown in FIGS. 17-20, system 400 includesboundary layer energizing members 430. Certain boundary layer energizingmembers 430 take the form of flow control devices (e.g., active flowcontrol devices) or ports or apertures 430 or the like. In exampleembodiments, boundary layer energizing members 430 are configured anddimensioned to alter (e.g., cause or prevent separation of) a fluidboundary layer over a flow control surface (e.g., over the turbineshroud assembly 310 and or ejector shroud assembly 320) to alter theperformance of the fluid turbine system 400 (or shrouds 110, 120 ofsystem 100, or shrouds 310, 320 of system 300, etc.). In exampleembodiments, the flow control ports or devices 430 employ high velocityflow through or via the ports 430 on aerodynamic surfaces of the system400 for flow control purposes (e.g., for the purpose of preventing orcausing separation of the boundary layer). In example embodiments, fluiddelivered to the flow control ports 430 can be provided by a suitableexternal pumping or actuation means or assembly or the like, and or canbe provided by harvesting fluid energy from within the shrouded fluidturbine system 400.

In general, at least one flow control port 430 is associated with and oris mounted with respect to a surface of system 400 (e.g., with a surfaceof turbine shroud assembly 310, or assembly 320). In exampleembodiments, a plurality of flow control ports 430 are associated with asurface of turbine shroud assembly 310 (or assembly 320). In someembodiments, the flow control ports 430 are integrally formed withassembly 310 (or assembly 320), although the present disclosure is notlimited thereto.

In certain embodiments, flow control ports 430 can be associated withand or positioned on the turbine shroud assembly 310 approximately at orproximal to the leading edge 312 of the turbine shroud assembly 310.However, it is noted that flow control ports 430 can be associated withor positioned on assembly 310 (or assembly 320) at any suitablelocation. For example, system 400 can include flow control ports 430 onthe suction side (e.g., low pressure side on the interior of the shroudassembly) and or on the pressure side (higher pressure side on theoutside or exterior of the shroud assembly) of shroud assembly surfaces(assembly 310 and or 320). As such, the flow control ports 430 can beconfigured and dimensioned to energize or provide fluid flow to theboundary layer to alter fluid flow (e.g., delay, cause or prevent flowseparation before the fluid has reached the trailing edge of the shroudassembly 310, 320).

It is noted that the flow control ports 430 can be utilized in lieu ofor in addition to the vortex generators 330 (or 130, etc.) in the fluidturbine systems of the present disclosure.

In example embodiments, the flow control ports or devices 430 employhigh velocity flow through or via the ports 430 on aerodynamic surfacesof the system 400 for preventing or causing separation of the boundarylayer. FIGS. 17-20 illustrate embodiments of the system 400 having flowcontrol ports 430 associated with the ringed airfoil surfaces (e.g.,assemblies 310, 320). It is noted that in excessive fluid velocityconditions, the flow devices or ports 430 can be disengaged so as toreduce the performance of the airfoils and therefore reduce the overallperformance of the turbine system 400. The flow devices or ports 430 maybe disengaged using a variety of means including active pneumatic orelectromechanical actuation, passive actuation due to velocity orpressure profile, or some combination thereof. One skilled in the artwill readily recognize that the above noted actuation means are merelyillustrative of sample embodiments and are not intended to be limitingin scope.

In example embodiments and as shown in FIG. 18, the flow control ports430 are associated with the inner surface of the turbine shroud 310proximal to the outwardly turning mixing elements 315. Again, it isnoted that ports 430 can be associated with or positioned on assembly310 (or assembly 320) at any suitable location. For example and as shownin FIGS. 19 and 20, flow control ports 430 can be associated with theouter surface of the turbine shroud 310 proximal to the inward turningmixing elements 317. Moreover and as shown in FIG. 19, flow controlports 430 can be associated with the inner surface of the ejector shroudassembly 320. As noted, fluid delivered to the flow control ports 430can be provided by a suitable external pumping or actuation means orassembly, and or can be provided by harvesting fluid energy from withinthe shrouded fluid turbine system 400.

FIG. 21 depicts another example embodiment of a shrouded fluid turbinesystem 500. The system 500 is a single shroud system free of an ejectorshroud. As such, an example embodiment of the fluid turbine system 500in accordance with the present disclosure is shown in FIG. 21. The fluidturbine system 500 includes a turbine shroud assembly 510, a nacellebody 550 and a rotor assembly 540. The turbine shroud assembly 510includes a front end 512 and a rear end 516. Support members 506 connectthe turbine shroud assembly 510 to the nacelle body 550.

The rotor assembly 540 includes a central hub 541, and the nacelle body550 and the turbine shroud assembly 510 are supported by a tower 502.The rotor assembly 540 and turbine shroud assembly 510 can be coaxialwith each other, i.e. they share a common central axis 505. The rear end516 of the turbine shroud assembly 510 has mixing elements, includingoutwardly directed mixing elements 515 and inwardly directed mixingelements 517.

In example embodiments and as shown in FIG. 21, system 500 includesboundary layer energizing members 530. Boundary layer energizing members530 can take the form of vortex generators and or flow control devicesor ports 530 or the like, as similarly discussed and described above inconjunction with FIGS. 1-20.

As noted above, boundary layer energizing members 530 are configured anddimensioned to alter a fluid boundary layer (e.g., prevent separation ofa fluid boundary layer) over a flow control surface (e.g., over theturbine shroud assembly 510) to alter the performance of the fluidturbine system 500. In general, at least one boundary layer energizingmember 530 is associated with and or is mounted with respect to asurface of system 500 (e.g., with a surface of turbine shroud assembly510). In example embodiments, a plurality of boundary layer energizingmembers 530 are associated with a surface of turbine shroud assembly510.

As discussed above in conjunction with FIGS. 1-20, it is noted thatboundary layer energizing member 530 can be associated with orpositioned on assembly 510 at any suitable location. For example, system500 can include members 530 on the suction side (e.g., low pressure sideon the interior of the shroud assembly) and or on the pressure side(higher pressure side on the outside or exterior of the shroud assembly)of shroud assembly surfaces (assembly 510). As such, members 530 can beconfigured and dimensioned to energize or provide fluid flow to theboundary layer to alter a fluid boundary layer (e.g., delay or preventflow separation before the fluid has reached the trailing edge of theshroud assembly 510).

Turning now to FIGS. 22-24, another example embodiment of a fluidturbine system 1500 in accordance with the present disclosure is shown.As discussed further below, FIGS. 22-24 illustrate a fluid turbinesystem 1500 having boundary layer energizing members 1530 (e.g., flowcontrol ports 1530) engaged with substantially faceted annular airfoilsurfaces. Boundary layer energizing members 1530 can take the form offlow control devices (e.g., active flow control devices) or ports 1530or the like, although the present disclosure is not limited thereto.Rather, it is noted that the boundary layer energizing members 1530 cantake other forms, e.g., vortex generators.

In example embodiments and as shown in FIG. 22, the turbine shroudassembly 1510 takes the form of an annular airfoil that includes aleading edge portion 1512 (also known as the inlet end). In certainembodiments, the leading edge 1512 is substantially annular, thusproviding a relatively narrow gap between the rotor blade tips of rotorassembly 1540 and the interior surface of the leading edge 1512. Theleading edge 1512 is engaged with a series of substantially linearsegments with constant cross sections 1515, also known as turbine shroudfacets, that transition from the annular leading edge 1512. Turbineshroud facets 1515 enjoin at nodes 1517, and further include rear ends1516, also known as the exit or trailing edge of the turbine shroudassembly 1510.

In some embodiments, a secondary shroud assembly 1520 (e.g., a shroudassembly in the shape of an annular airfoil) includes substantiallylinear segments with constant cross sections 1535, otherwise referred toas ejector shroud facets, and include leading edges 1522 and trailingedges 1524 that are in fluid communication with the trailing edge 1516of the turbine shroud assembly 1510. Facets 1535 enjoin at nodes 1537.Facets 1535 also enjoin at struts 1513 that support the nodes 1517, 1537of both shroud assemblies 1510, 1520. The shroud assemblies 1510, 1520are co-axial with the rotor assembly 1540, rotor hub 1541 and nacellebody 1550 about the central axis 1505. The rotor assembly 1540 andshroud assemblies 1510, 1520 are supported by a tower structure 1502.

In certain embodiments and as shown in FIGS. 22-24, system 1500 includesboundary layer energizing members 1530. Boundary layer energizingmembers 1530 take the form of flow control devices or ports or apertures1530 or the like. In general, boundary layer energizing members 1530 areconfigured and dimensioned to alter a fluid boundary layer (e.g.,prevent separation of a fluid boundary layer) over a flow controlsurface (e.g., over the turbine shroud assembly 1510 and or ejectorshroud assembly 1520) to alter the performance of the fluid turbinesystem 1500. In general, the flow control ports or devices 1530 employhigh velocity flow through or via the ports 1530 on aerodynamic surfacesof the system 1500 for flow control purposes. In example embodiments,fluid delivered to the flow control ports 1530 can be provided by asuitable external pumping or actuation means or assembly, and or can beprovided by harvesting fluid energy from within the shrouded fluidturbine system 1500.

In general, at least one flow control port 1530 is associated with andor is mounted with respect to a surface of system 1500 (e.g., with asurface of turbine shroud assembly 1510, or assembly 1520). A pluralityof flow control ports 1530 can be associated with a surface of turbineshroud assembly 1510 (or assembly 1520).

Flow control ports 1530 can be associated with and or positioned on theturbine shroud assembly 1510 approximately at or proximal to the leadingedge 1512 of the turbine shroud assembly 1510. However, it is noted thatflow control ports 1530 can be associated with or positioned on assembly1510 (or assembly 1520) at any suitable location (e.g., on the suctionside of a shroud assembly, on the pressure side 1538 of a shroudassembly, etc.). As such, the flow control ports 1530 can be configuredand dimensioned for flow control purposes (e.g., to energize or providefluid flow to the boundary layer to delay or prevent flow separationbefore the fluid has reached the trailing edge of the shroud assembly1510, 1520).

As shown in FIGS. 23-24, flow control ports 1530 are associated with theinner surface of the turbine shroud assembly 1510 proximal to theoutward leading edge 1512. Flow control ports 1530 are also associatedwith the inner surface of the ejector shroud assembly 1520. By providingfluid flow through the ports 1530, boundary layer attachment over theaerodynamic surfaces may be maintained or disrupted by varying volumeand or angle of flow through ports 1530, and in so doing providing ameans of increasing or decreasing performance of turbine system 1500(e.g., airfoil performance). As noted, fluid delivered to the flowcontrol ports 1530 can be provided by a suitable external pumping oractuation means or assembly, and or can be provided by harvesting fluidenergy from within the shrouded fluid turbine system 1500.

Although the systems and methods of the present disclosure have beendescribed with reference to example embodiments thereof, the presentdisclosure is not limited to such example embodiments and orimplementations. Rather, the systems and methods of the presentdisclosure are susceptible to many implementations and applications, aswill be readily apparent to persons skilled in the art from thedisclosure hereof. The present disclosure expressly encompasses suchmodifications, enhancements and or variations of the disclosedembodiments. Since many changes could be made in the above constructionand many widely different embodiments of this disclosure could be madewithout departing from the scope thereof, it is intended that all mattercontained in the drawings and specification shall be interpreted asillustrative and not in a limiting sense. Additional modifications,changes, and substitutions are intended in the foregoing disclosure.Accordingly, it is appropriate that the appended claims be construedbroadly and in a manner consistent with the scope of the disclosure.

What is claimed is:
 1. A shrouded fluid turbine system comprising: arotor assembly; a turbine shroud assembly disposed about the rotorassembly, the turbine shroud having a low pressure side and a highpressure side, the low pressure side in fluid communication with therotor assembly; and at least one boundary layer energizing memberassociated with the turbine shroud assembly, the at least one boundarylayer energizing member configured and dimensioned to alter a fluidboundary layer over a surface of the turbine shroud assembly to alterthe performance of the fluid turbine system.
 2. The system of claim 1,wherein the at least one boundary layer energizing member is positionedproximal to a leading edge of the turbine shroud assembly.
 3. The systemof claim 1 further comprising a first plurality of boundary layerenergizing members and a second plurality of boundary layer energizingmembers; wherein the first plurality of boundary layer energizingmembers are positioned proximal to a leading edge of the turbine shroudassembly; and wherein the second plurality of boundary layer energizingmembers are positioned between the leading edge and a trailing edge ofthe turbine shroud assembly.
 4. The system of claim 3, wherein the firstand second pluralities of boundary layer energizing members areassociated with the low pressure side of the turbine shroud assembly. 5.The system of claim 1 further comprising a plurality of boundary layerenergizing members; wherein the turbine shroud assembly includes aplurality of curving mixing elements; and wherein each mixing element isassociated with at least one boundary layer energizing member.
 6. Thesystem of claim 5, wherein the plurality of curving mixing elementsincludes a first plurality of inwardly curving mixing elements and asecond plurality of outwardly curving mixing elements.
 7. The system ofclaim 6, wherein at least one boundary layer energizing member ispositioned on the high pressure side of the turbine shroud assembly andproximal to an inward curving mixing element of the plurality of inwardcurving mixing elements.
 8. The system of claim 1, wherein the turbineshroud assembly defines an airfoil ring having an apex; and wherein theat least one boundary layer energizing member is positioned proximal tothe apex of the airfoil ring.
 9. The system of claim 1, wherein the atleast one boundary layer energizing member is a vortex generator, thevortex generator in the form of a protruding member that protrudes froma surface of the turbine shroud assembly.
 10. The system of claim 9,wherein the vortex generator has a length and a height; and wherein thelength is about four times the height of the vortex generator.
 11. Thesystem of claim 9, wherein the vortex generator has a length and aheight; wherein the vortex generator is fabricated from a flexiblematerial and includes a first un-flexed condition and a second flexedcondition; and wherein when the vortex generator is in the second flexedcondition, the length of the vortex generator is about eight times theheight.
 12. The system of claim 5, wherein each curving mixing elementincludes a voluminous leading edge that transitions to a curved planarform at a trailing edge.
 13. The system of claim 1 further comprising anejector shroud assembly positioned downstream from and coaxial with theturbine shroud assembly; wherein at least one boundary layer energizingmember is associated with the ejector shroud assembly, the at least oneboundary layer energizing member associated with the ejector shroudassembly configured and dimensioned to alter a fluid boundary layer overa surface of the ejector shroud assembly to alter the performance of thefluid turbine system.
 14. The system of claim 13, wherein the at leastone boundary layer energizing member associated with the ejector shroudassembly is positioned proximal to a leading edge of the ejector shroudassembly.
 15. The system of claim 13 further comprising a firstplurality of boundary layer energizing members and a second plurality ofboundary layer energizing members associated with the ejector shroudassembly; wherein the first plurality of boundary layer energizingmembers are positioned proximal to a leading edge of the ejector shroudassembly; and wherein the second plurality of boundary layer energizingmembers are positioned between the leading edge and a trailing edge ofthe ejector shroud assembly.
 16. The system of claim 15, wherein thefirst and second pluralities of boundary layer energizing members areassociated with the low pressure side of the ejector shroud assembly.17. The system of claim 13, wherein the ejector shroud assembly definesan airfoil ring having an apex; and wherein the at least one boundarylayer energizing member associated with the ejector shroud assembly ispositioned proximal to the apex of the airfoil ring.
 18. The system ofclaim 13, wherein the at least one boundary layer energizing memberassociated with the ejector shroud assembly is a vortex generator, thevortex generator in the form of a protruding member that protrudes froma surface of the ejector shroud assembly.
 19. The system of claim 1,wherein the at least one boundary layer energizing member is a flowcontrol port, the flow control port configured and dimensioned to employhigh velocity flow through the flow control port for flow controlpurposes and to alter a fluid boundary layer over a surface of theturbine shroud assembly to alter the performance of the fluid turbinesystem.
 20. The system of claim 19, wherein the at least one flowcontrol port is positioned proximal to a leading edge of the turbineshroud assembly.
 21. The system of claim 19, wherein the at least oneflow control port is remotely energized with the high velocity flow. 22.The system of claim 19, wherein the at least one flow control port isenergized with the high velocity flow by harvesting fluid energy fromthe fluid turbine system.
 23. The system of claim 1, wherein the atleast one boundary layer energizing member is configured and dimensionedto prevent separation of a fluid boundary layer over a surface of theturbine shroud assembly to alter the performance of the fluid turbinesystem.
 24. The system of claim 1, wherein the at least one boundarylayer energizing member is configured and dimensioned to alter a fluidboundary layer over a surface of the turbine shroud assembly to reducethe performance of the fluid turbine system.
 25. The system of claim 1,wherein the turbine shroud assembly defines an annular airfoil having aleading edge that transitions to a faceted trailing edge.
 26. The systemof claim 19, wherein the volume or angle of the high velocity flowthrough the flow control port is variable.
 27. The system of claim 1,wherein the at least one boundary layer energizing member configured anddimensioned to alter a fluid boundary layer over a surface of theturbine shroud assembly alters the performance of the fluid turbinesystem.
 28. A shrouded fluid turbine system comprising: a rotorassembly; a turbine shroud assembly disposed about the rotor assembly,the turbine shroud having a low pressure side and a high pressure side,the low pressure side in fluid communication with the rotor assembly,the turbine shroud assembly including a plurality of curving mixingelements; and a first and second plurality of boundary layer energizingmembers associated with the turbine shroud assembly, each boundary layerenergizing member configured and dimensioned to alter a fluid boundarylayer over a surface of the turbine shroud assembly, the first pluralityof boundary layer energizing members positioned proximal to a leadingedge of the turbine shroud assembly and the second plurality of boundarylayer energizing members positioned between the leading edge and atrailing edge of the turbine shroud assembly, at least a portion of thefirst and second pluralities of boundary layer energizing membersassociated with the low pressure side of the turbine shroud assembly,and each mixing element associated with at least one boundary layerenergizing member.
 29. A shrouded fluid turbine system comprising: arotor assembly; a turbine shroud assembly disposed about the rotorassembly, the turbine shroud having a low pressure side and a highpressure side, the low pressure side in fluid communication with therotor assembly; at least one first boundary layer energizing memberassociated with the turbine shroud assembly, the at least one firstboundary layer energizing member configured and dimensioned to alter afluid boundary layer over a surface of the turbine shroud assembly toalter the performance of the fluid turbine system; an ejector shroudassembly positioned downstream from and coaxial with the turbine shroudassembly; at least one second boundary layer energizing memberassociated with the ejector shroud assembly, the at least one secondboundary layer energizing member configured and dimensioned to alter afluid boundary layer over a surface of the ejector shroud assembly toalter the performance of the fluid turbine system; wherein the turbineshroud assembly includes a plurality of curving mixing elements; whereinthe at least one first boundary layer energizing member is positionedproximal to a leading edge of the turbine shroud assembly; and whereinthe at least one second boundary layer energizing member is positionedproximal to a leading edge of the ejector shroud assembly.